The invention relates to the tuning of cavities in photonic crystal lattice structures.
Photonic crystals are periodic structures of high and low refractive index media that confine light of certain wavelengths. Photonic crystals may be used to make a number of optical components such as waveguides and filters.
For optical communications, light in the wavelength range of 1.3 xcexcm to 1.5 xcexcm is typically used because of low absorption in silica waveguides. Hence, this wavelength range is of interest for present-day optical networks. The manufacture of photonic crystals to operate in this wavelength range is typically subject to a high degree of manufacturing variance. Hence, it is desirable for wavelength discrimination applications to have a method and structure to allow tuning of the photonic crystal apparatus to respond to a specific wavelength.
In accordance with the invention, a movable feature such as a tuning stub is introduced into a photonic crystal that allows for controllable tuning of cavities that are created within the photonic crystal. Cavities to be tuned in accordance with the invention are designed to work in the spectrum from far infrared to hard ultraviolet region. Attaching the feature to an actuator allows the feature to be moved in and out of the photonic crystal for precise tuning. The invention may typically be implemented using either polysilicon or amorphous silicon.